Hemostasis is the physiological process that stops bleeding. Functional hemostasis requires the balanced engagement of plasma coagulation factors to initiate clotting, adequate fibrinogen to form the fibrin mesh, platelets to modulate factor function and to mechanically stiffen the fibrin mesh, and fibrinolytic enzymes to dissolve the clot when its useful life is over. Perturbation of any of these subsystems can disrupt hemostasis; either by impeding the cessation bleeding or by initiating clotting when it is unneeded. Disruptions of hemostasis contribute significantly to morbidity and mortality in patients suffering from heart disease, stroke, traumatic injury, cancer, and sepsis.
While hemostatic dysfunction impacts a broad range of medical conditions, it has been studied with particular intensity in cardiac surgery. Cardiac bypass surgery is associated with significant post-operative bleeding. This is caused by a combination of platelet damage by the bypass pump, factor and fibrinogen consumption associated with surgical trauma, and the occasional presence of residual anti-coagulant. A number of strategies are currently used to manage this dysfunction. The crudest strategy is a “shotgun therapy” approach; transfusing varying combinations of fresh frozen plasma, cryoprecipitate or fibrinogen concentrate, and platelet concentrate. This approach is often successful in controlling bleeding, however unnecessary transfusion carries a significant financial cost and increases patient morbidity and mortality. Recognition of the risks associated with excessive transfusion have led to increasingly specific and detailed guidelines to manage transfusion. These guidelines call for transfusion to be guided by point-of-care tests that assess hemostatic function in a timely and accurate manner.
A broad range of approaches have been proposed to fill the need for point-of-care hemostasis testing. These technologies can be separated into broad categories: clot-time assays, platelet-only tests, and viscoelastic tests. Clot-time assays can be implemented in simple systems, however a rapidly forming clot may not be a physiologically useful clot, so clot-time results may have limited clinical value. Moreover, clot-time assays generally operate on plasma, rather than whole blood, and therefore typically neglect the important interactions between plasma coagulation factors and platelets. Platelet-only tests provide useful information, but are also limited in that they neglect interactions between platelets and plasma coagulation factors. Viscoelastic tests have been shown to provide highly useful data. However, their operational complexity has traditionally limited their point-of-care utility. None of the currently available point-of-care tests adequately assess hemostatic function in a timely and accurate manner. A fast, accurate test is therefore still needed to fill this gap.
Other systems, methods, features and/or advantages will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be protected by the accompanying claims.